A Switched Reluctance Motor (SRM) is an electric motor that operates based on the principle of magnetic reluctance. It is a type of synchronous motor, meaning its rotor moves in sync with the rotating magnetic field produced by the stator windings. However, unlike conventional synchronous motors, SRMs do not have permanent magnets on the rotor or the stator.
The main components of a Switched Reluctance Motor are the stator and the rotor. The stator is the stationary part of the motor and consists of a series of electromagnet coils, typically arranged in a circular pattern. These coils are energized sequentially in a specific sequence to create a rotating magnetic field.
The rotor, on the other hand, is the moving part of the motor and is typically made of a simple steel structure with salient poles or teeth. The rotor does not have any windings or magnets and relies on the principle of magnetic reluctance. Magnetic reluctance refers to the tendency of magnetic materials to align themselves with the magnetic field, seeking the path of least resistance for magnetic flux.
The operation of an SRM is based on the concept that when a magnetic circuit (such as the rotor in an SRM) tries to align itself with a magnetic field, it will experience a torque that pulls it into alignment. Conversely, when the magnetic circuit tries to move away from alignment, it experiences a force opposing that movement.
To make the rotor rotate, the stator coils are energized sequentially in a manner that aligns the rotor poles with the stator poles. This creates an attractive force between the rotor and stator poles, causing the rotor to align with the rotating magnetic field. As the rotor approaches alignment, the stator coil is switched off, and the rotor moves to the next position due to its inertia. This process is repeated continuously, driving the rotor in a rotational motion.
SRMs have several advantages, including simple construction, high reliability due to the absence of brushes or permanent magnets, and potential cost savings. However, they also have some challenges, such as higher acoustic noise and vibration compared to other motor types, and they require more complex control electronics to manage the switching of stator coils accurately.
In recent years, there has been renewed interest in SRMs due to advancements in power electronics and control systems, making them a viable option for various applications, including industrial machinery, electric vehicles, and renewable energy systems.